High temperature annealing effects on deep-level defects in a high purity semi-insulating 4H-SiC substrate

高純度半絶縁性六方晶炭化ケイ素基板中の深い準位の高温熱処理効果

岩本 直也*; Azarov, A.*; 大島 武; Moe, A. M. M.*; Svensson, B. G.*

Iwamoto, Naoya*; Azarov, A.*; Oshima, Takeshi; Moe, A. M. M.*; Svensson, B. G.*

Influence of high-temperature annealing on deep-level defects in a high-purity semi-insulating hexagonal (4H) silicon carbide (SiC) substrates was studied. From secondary ion mass spectrometry, it was found that the substrates contained boron (B) with concentration in the mid 10 /cm range while other impurities including nitrogen, aluminum, titanium, vanadium and chromium were below their detection limits. Schottky barrier diodes (SBDs) were fabricated on substrates annealed at 14001700 C. The series resistance of the SBDs decreased with increasing annealing temperature. Admittance spectroscopy results showed the presence of shallow B acceptors and deep-level defects. By 1400 C annealing, the B acceptors were still compensated by deep-level defects. However, the concentration of deep-level defects decreased with increasing annealing temperature above 1400 C. Therefore, the decreases in series resistance due to high temperature annealing can be interpreted in terms of annealing of deep-level defects which act as compensation centers for B acceptors.